Even just single IM injection can cause CPK level in 1000, more over patient was agitated. You did not mention about, if patient received any prn medications or not. I guess patient is not on any Anticholinergic medications. If so, this might be a case of Anticholinergic delirium.
This may not be NMS because....
1. In NMS, CK is typically more than 1000 IU/L and can be as high as 100,000 IU/L.
particularly in the mild to moderate range, is not specific for NMS and is often seen in patients with acute and chronic psychosis due to intramuscular injections and physical restraints, and sometimes without specific explanation.
2.A consistent laboratory finding is leukocytosis, with a white blood cell count typically 10,000 to 40,000/mm3
3. Hyporeflexia
4.Hyperthermia is a defining symptom according to many diagnostic criteria. Temperatures of more than 38ºC are typical (87 percent), but even higher temperatures, greater than 40ºC, are common (40 percent).
5.Autonomic instability typically takes the form of tachycardia (in 88 percent), labile or high blood pressure (in 61 to 77 percent), and tachypnea (in 73 percent) Dysrhythmias may occur.
6. Diaphoresis is often profuse.
